"Unique" Robots - These are the rarest robots! They always have at least one extremely rare component. You should feel special if you are able to complete them!
"Functional" Robots have some type of effect on the way you play the game.
For example, a robot that has "+1 energy" next to it will increase your energy cap by 1 upon completion!
"Transitrons" allow you to access batches of new robots at a time.